Discussion»Questions»Food and Drink» Peppers range in heat from the 'Pepper X', at 3.18 million Scoville units, to 0 for common bell peppers and others.
Bhut jolokia (ghost pepper), at 1.041m SHU, is probably the hottest used commercially. Weirdies like Pepper X and Trinidad Scorpion were only bred to try to set Scoville records, nobody is dumb enough to actually EAT them.
There are pepper eating contests here, along with Guinness records. I would never use anything hotter than a Thai hot for cooking. I grew some for a couple of years. Even if you don't eat them the plant is beautiful when all of its small red peppers have grown.